Lubricating oil manufacture



Patented Jan. 16, 1945 um'rno STATE s PATENT or ies."

LUBRICATING OIL MANUFACTURE Frederic C. McCoy and Charles C. Towne, Beacon, N. Y., assignors to The Texas Company, New York, N. Y., a corporation of Delaware No Drawing. Application March 17, 1942,

Serial No. 435,109

scl ims, ,(01. 196-18) V wax crystal modifier or regulator effective for.

either reducing the pour point of wax-bearing oil or facilitating separation of wax from the oil' or both, a substance consisting essentially, of sulfurized esters of fatty acids and particularly sulfulrized non-glyceride fatty material such as sperm oi It has been proposed heretofore to employ sulfurized materials as additives to oil for the pur-' pose of imparting oiliness and other characteristics. However, it has now been discovered that sulfurized esters of fatty acids and particularly sulfurized sperm oil possess the ability to modify or regulate wax crystal structure in wax-bearing oils. The addition of this material to wax-bearing oil and particularly to residual wax-bearing oils of relatively low wax content inhibits wax crystal growth and renders the wax crystals more dense. Reduction in crystal size, or increasing the density of the wax crystals in lubricating oil stocks permits the oil to pour at lower temperatures and also facilitates separation of the wax from a chilled dilute wax-bearing oil mixture by filtration.

The wax crystal modifier of this invention may be prepared from a sperm oil having a specific gravity of about 0378-0384 (60/60 F.), a Saybolt Universal viscosity at 100 F. of about 95 to 110 and a saponification number of 125 to 135.

Sperm oil of the foregoing characteristics is re acted with suitable amounts of sulfur at temperatures in the range about 300 to 385 F., the re:-

action being continueduntil the sulfur is combined in the form of neutral organic sulfur compounds.

The resulting sulfurized sperm oil will have an A. P. I. gravity of about 15.1, a Saybolt Universal viscosity at 210 F. of about 219 and a pour point temperature of about 55 F. and will contain. about 10% of combined sulfur. The product is; substantially free from fatty acids and glyceride s i It thus consists essentially of a sulfurized fat containing about 10% combined sulfur. By way of specific example, a small amount of this sulfurized sperm oil was added to a partially dewaxed residual lubricating oil stock, the amount added being about 3% by weight of the partially dewaxed lubricating oil stock. The residual lubricating oil stock had the following ap proximate characteristics: 1

Gravity A. P. T I 25.0 Saybolt Universal viscosity at 210 94 Pour point, F

The addition of 3% sulfurized sperm oil to this 'oil resulted in reducing the pour point to about minus 15 to minus 20 F. In other words, there was areduction of about 15 to 20 in pour point this material to the oil. Thus, this modifier appears to be superior to many substances proposed heretofore since it is quite effective in reducing the pour point of residual lubricating oil stocks.

It is therefore contemplated that the invention is of particular advantage in reducing the pour point of partially dewaxed residual oil or of residual type oils which, in the absence of an added modifier, have a pour point not exceeding about 25 F.-

It is alsocontemplated that the modifier may be used as a dewaxing aid. In such case the waxbearing oil-to be dewaxed is advantageously mixed with a suitable diluent or dewaxing solvent and chilled to a dewaxing temperature at which the wax is precipitated in solid form. The precipitated. wax is then separated from the chilled mixture in the presence of a small amount of the modifier or regulator substance, the separation advantageously being effected by filtration.

In a dewaxing operation of this character the modifier is usually incorporated in the wax-'bearing oil or a diluted wax-bearing oil mixture prior to chi1ling, the amount so added ranging from about'a fraction of a per cent to 3 or 5% by weight of the wax-bearing oil charged.

The dewaxing operation may be carried out so as to effect only partial removal of the wax, as,

for example, dewaxing at a temperature of about 0 to minus 10 F., advantage being taken of the pour depressing effect of modifying material remaining in the oil from which the wax has been separated to depress the pour point still further.

Such dewaxing operations can be carried out using conventional solvents and conventional methods of wax separation which are now well known and understood in the art so that a detailed description thereof is unnecessary. For example, customary diluents or solvents employed may comprise low boiling hydrocarbons, either normally gaseous or normally liquid or selective solvent mixtures such as mixtures of aliphatic ketones and aromatic hydrocarbons including benzol and toluol.

While sulfurized sperm oil has been specifically described, nevertheless it is contemplated that other sulfurized neutral mono-esters of fatty acids may be employed such as methyl and ethyl oleates, glycol oleate, butyl stearate, isopropyl stearate, etc.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. In the manufacture of low pour test lubricating oil from wax-bearing oil, the steps comprising diluting and chilling the wax-bearing oil to a temperature at which wax is precipitated therefrom, and separating the precipitated wax from the mixture by filtration in the presence of a small quantity, not in excess of 3 to 5% by weight of the wax-bearing oil, of a wax crystal modifier consisting essentially of a sulfurized mono-ester of a fatty acid.

2. In the manufacture of low pour test lubricating oil from wax-bearing oil, the steps comprising diluting and chilling the wax-bearing oil to a temperature at which waxis precipitated therefrom, and separating the precipitated wax from the mixture in the presence of a small quantity, not in excess of 3 to 5% by weight of the wax-bearing oil, of a wax crystal modifier weight of the wax-hearing oil, of a wax crystal modifier consisting essentially of a sulfurized non-glyceride fat containing about 10% combined sulfur.

FREDERIC C. MCCOY. CHARLES C. TOV/NE. 

